diff --git a/.github/scripts/test_desktop_swift_ci_contract.py b/.github/scripts/test_desktop_swift_ci_contract.py
index f12ebf2f3e1..9b94c84d5f1 100755
--- a/.github/scripts/test_desktop_swift_ci_contract.py
+++ b/.github/scripts/test_desktop_swift_ci_contract.py
@@ -149,6 +149,8 @@ def test_closed_prs_release_the_same_pr_concurrency_group_without_allocating_a_r
         changes = self.jobs["changes"]
 
         self.assertRegex(workflow, r"types:\s*\[[^]]*closed[^]]*\]")
+        self.assertIn("github.event.action == 'closed' && github.event.pull_request.merged", workflow)
+        self.assertIn("format('merged-{0}', github.event.pull_request.number)", workflow)
         self.assertIn("github.event.pull_request.number || github.sha", workflow)
         self.assertIn(
             "cancel-in-progress: ${{ github.event_name == 'pull_request' && (github.event.action != 'closed' || !github.event.pull_request.merged) }}",
@@ -255,7 +257,7 @@ def test_later_main_push_cannot_cancel_exact_sha_release_evidence(self):
         # push gets an immutable group and therefore runs its own exact-SHA
         # Build & Tests and Release Compile checks to a terminal conclusion.
         self.assertIn(
-            "group: desktop-swift-${{ github.event.pull_request.number || github.sha }}",
+            "group: desktop-swift-${{ (github.event.action == 'closed' && github.event.pull_request.merged && format('merged-{0}', github.event.pull_request.number)) || github.event.pull_request.number || github.sha }}",
             concurrency,
         )
         self.assertIn(
diff --git a/.github/workflows/desktop-swift-ci.yml b/.github/workflows/desktop-swift-ci.yml
index ed19428a49f..2ac82198427 100644
--- a/.github/workflows/desktop-swift-ci.yml
+++ b/.github/workflows/desktop-swift-ci.yml
@@ -10,7 +10,7 @@ on:
 concurrency:
   # Supersede stale revisions of the same PR, but never let a later main push
   # cancel the exact-SHA evidence consumed by desktop release planning.
-  group: desktop-swift-${{ github.event.pull_request.number || github.sha }}
+  group: desktop-swift-${{ (github.event.action == 'closed' && github.event.pull_request.merged && format('merged-{0}', github.event.pull_request.number)) || github.event.pull_request.number || github.sha }}
   # An abandoned PR's `closed` run may cancel obsolete work. A merged PR's
   # bookkeeping run must not cancel exact-SHA evidence still finishing for the
   # merge, so only unmerged closures retain cancellation authority.